1. Field of the Invention
This invention relates to a shutter device having a charge mechanism.
2. Description of Related Art
The charge mechanism of an ordinary focal plane shutter, i.e., a mechanism for moving shutter blades from an exposure completed state to an exposure start state and for charging a driving spring for driving the shutter blades, is generally arranged to move, against an urging force of the driving spring, a driving lever which engages the shutter blades and receives the urging force of the driving spring, from the exposure completed state to the exposure start state.
Further, the charge mechanism is provided with a return spring which is exclusively used to bring the charge mechanism back to its initial position upon completion of the charging action of the charge mechanism, that is, after the driving lever is moved to the exposure start state.
As a result of efforts to expand a photo-taking capability range, focal plane shutters of these days are being arranged to have a higher flash synchronizing speed and to have a higher blade travel speed for increasing a maximum shutter speed.
The increased traveling speed of shutter blades has prompted use of shutter blade driving springs having a stronger spring force. The use of the driving spring having a stronger spring force in turn necessitates a great increase in shutter charging force of the charge mechanism of a shutter device.
However, since it is a general trend to reduce the size and weight of a camera using such a shutter device, the possible extent of increase in shutter charging force for the shutter device is limited.